1. Field of the Invention
The present invention relates to a vehicle including a tiltable vehicle body frame and two front wheels.
2. Description of the Related Art
A known vehicle includes a vehicle body frame that is tilted in the left-right direction during the cornering of the vehicle and two front wheels provided so as to be arranged in the left-right direction of the vehicle body frame (for example, see German Patent Publication No. 10 2010 052 716 A, International Publication No. WO 2012/007819, U.S. Design Pat. No. D547,2425, and Catalogo partidi ricambio, MP3 300 ie LT Mod. ZAPM64102, Piaggio).
The vehicle including the tiltable vehicle body frame and the two front wheels further includes a link mechanism. The link mechanism includes an upper cross member and a lower cross member. Furthermore, the link mechanism also includes a right side rod and a left side rod. The right side rod supports the right end portions of the upper cross member and the lower cross member. The left side rod supports the left end portions of the upper cross member and the lower cross member. The intermediate portions of the upper cross member and the lower cross member are supported on the vehicle body frame at a position directly in front of a steering shaft. The upper cross member and the lower cross member are supported on the vehicle body frame so as to be turnable about axes extending substantially in the front-rear direction of the vehicle body frame. The upper cross member and the lower cross member are turned relative to the vehicle body frame in cooperation with the tilting of the vehicle body frame such that the relative positions of the two front wheels in the up-down direction of the vehicle body frame are changed. In the upright state of the vehicle body frame, the upper cross member and the lower cross member are located above the two front wheels in the up-down direction of the vehicle body frame.
The vehicle including the tiltable vehicle body frame and the two front wheels further includes a right shock absorber and a left shock absorber. The right shock absorber supports the right front wheel so that the right front wheel is movable in the up-down direction of the vehicle body frame. The left shock absorber supports the left front wheel so that the left front wheel is movable in the up-down direction of the vehicle body frame. The right shock absorber is supported on the right side rod so as to be turnable about the axis of the right side rod. The right shock absorber includes a right shock-absorbing member and a right bracket to support the right shock-absorbing member. The left shock absorber is supported on the left side rod so as to be turnable about the axis of the left side rod. The left shock absorber includes a left shock-absorbing member and a left bracket to support the left shock-absorbing member. The vehicles described in German Patent Publication No. 10 2010 052 716 A and International Publication No. WO 2012/007819 further include a handle bar, a steering shaft, and a turn transmitting mechanism. The handle bar is fixed to the steering shaft. The steering shaft is turnably supported on the vehicle body frame. When the handle bar is steered, the steering shaft is also turned. The turn transmitting mechanism transmits the turning of the steering shaft to the right shock absorber and to the left shock absorber.
The vehicle including the tiltable vehicle body frame and the two front wheels further includes numerous on-vehicle components on the periphery of the steering shaft. The on-vehicle components are, for example, lighting devices such as a headlight, a radiator, a reservoir tank, electric devices such as a horn, a vehicle main switch, a storage box, a storage pocket and the like.
The vehicles described in German Patent Publication No. 10 2010 052 716 A and International Publication No. WO 2012/007819 include a link mechanism on the periphery of the steering shaft so that the link mechanism is moved in cooperation with the titling of the vehicle body frame. Hence, in the vehicle including the tiltable vehicle body frame and the two front wheels, when the on-vehicle components are located around the periphery of the steering shaft, the components are required to be spaced away from the movable range of the link mechanism. For this reason, in the vehicle including the tiltable vehicle body frame and the two front wheels, the structure provided around the periphery of the steering shaft is liable to become bulky.
In the vehicle disclosed in German Patent Publication No. 10 2010 052 716 A, a turn transmitting mechanism is disposed between the lower cross member and the right and left brackets in the up-down direction of the vehicle when the vehicle is viewed from the front. The lower cross member, the turn transmitting mechanism, and the left and right brackets are moved in the up-down direction in cooperation with one another. Since their movable ranges overlap with one another, the structure around the periphery of the steering shaft is not liable to become bulky even if on-vehicle components such as a headlight and auxiliary devices are provided. On the other hand, in the tilted state of the vehicle body frame, it is necessary to secure clearances between the turn transmitting mechanism and the right shock absorber and between the turn transmitting mechanism and the left shock absorber. Hence, each of the right bracket and the left bracket includes a slanted portion slanted inward toward the center in the vehicle width direction, and the shock-absorbing member is connected to the lower end portion of the slanted portion. Accordingly, it is possible to secure the clearances between the turn transmitting mechanism and the right shock absorber and between the turn transmitting mechanism and the left shock absorber, not only in the upright state of the vehicle body frame but also in the tilted state thereof. However, since each of the right bracket and the left bracket includes the slanted portion, the extension/contraction lengths of the right shock-absorbing member and the left shock-absorbing member become short. When the extension/contraction lengths of the shock-absorbing members are not sufficiently long, the impact forces applied to the two front wheels are hardly absorbed. As a result, in the vehicle disclosed in German Patent Publication No. 10 2010 052 716 A, an enlargement of the structure around the periphery of the steering shaft is suppressed but the riding comfort of the vehicle is degenerated.
In the vehicle disclosed in International Publication No. WO 2012/007819, the turn transmitting mechanism is curved upward when the vehicle is viewed from the front. In addition, a portion of the turn transmitting mechanism overlaps with the lower cross member. Hence, the extension/contraction lengths of the shock-absorbing members are sufficiently long while securing the clearances between the turn transmitting mechanism and the right shock absorber and between the turn transmitting mechanism and the left shock absorber. However, the space ahead of the lower cross member is eventually used as the movable range of the turn transmitting mechanism. Since the turn transmitting mechanism is moved in cooperation with the link mechanism and the steering of the handle bar, its movable range is large. Hence, it is necessary to configure the turn transmitting mechanism so that the movable range of the link mechanism does not interfere with the movable range of the turn transmitting mechanism. Furthermore, when the on-vehicle components such as a headlight and auxiliary devices are included, it is necessary to avoid the movable range of the link mechanism and the movable range of the turn transmitting mechanism. As a result, in the vehicle disclosed in International Publication No. WO 2012/007819, the riding comfort of the vehicle is secured but the structure around the periphery of the steering shaft eventually becomes bulky.